This invention relates generally to venting mechanisms and more specifically to venting mechanisms for drive axle assemblies and the like.
A drive axle assembly is designed to transfer power. To do this a number of gears inside of a housing are used, and these gears need to be lubricated. When these gears operate, they generate heat and heat up surrounding lubricant and air, increasing air pressure inside the housing. Intense pressure build up can cause problems such as lubricant leakage which could lead to unnecessary gear wear. Consequently, drive axle assemblies and other gearing devices for transmitting power commonly use an air vent to relieve the pressure.
But the use of an air vent introduces another problem in that the air vent provides an escape path for the lubricant if the lubricant is near the air vent. Action of the gears inside of the housing, especially large gears which are partially submerged in the lubricant, compound the problem by churning and splashing the lubricant inside the housing. This creates possibilities of the lubricant coming in close contact with the air vent and escaping regardless of where the air vent is located.
Prior attempts to solve the problem of lubricant escape through an air vent are known. One known attempt places the air vent mechanism high above the level of lubricant so as to keep the lubricant away from the air vent, such as shown in the U.S. Pat. No. 4,554,844 granted to Hideo Hamano on Nov. 26, 1985. This patent discloses an air breather assembly 50 for a differential gear unit 26. The air breather assembly 50 includes an air breather plug 56, a vent hole 54 and a cover member 18. The air breather assembly 50 is placed high above the level of lubricant in a sump and it has an air passage which is designed to reduce the chance the lubricant has to escape. But problems can occur when the lubricant is splashed by gears directly at the air breather assembly. When this happens the lubricant could escape through the air breather assembly even though it is above the level of lubricant in the sump.
Another prior art attempt uses a fixed deflector to deflect lubricant and keep it away from the air vent, such as shown in U.S. Pat. No. 4,351,203 granted to Koichi Fukunaga on Sept. 28, 1982. This patent discloses a breather plug assembly 4 with a deflector 5 to deflect a flow of lubricant Q and keep it away from the breather plug assembly. The deflector 5 has four equiangularly spaced openings 55 in its walls. But problems could occur due to the fact that the deflector is fixed in one position. When the lubricant is splashed high or in different direction it could cause the lubricant to avoid the deflector and be forced out of the breather plug assembly.